1. Technical Field
The present disclosure generally relates to an apparatus for processing a substrate and, particularly, to an apparatus for wet processing a substantially rectangular printed circuit board (PCB).
2. Description of Related Art
In the manufacture of PCBs, it is normal practice to feed the boards through a series of processing machines via a conveyor system. The process includes resit stripping, pre-cleaning, etching, neutralizing, water rinsing, and drying. Pre-cleaning, etching, neutralizing, and water rinsing, are known as wet process steps. In these wet process steps, a spray system comprising at least one set of spray nozzles connected to spray pipes is arranged to face the conveyor system to spray PCBs on the conveyor system, such as with etchant to form circuits. The etchant is supplied by a dosing system, which is capable of supplying a constant predetermined amount of etchant.
However, the PCBs on the conveyor system will often be of different sizes. When such PCBs are conveyed to be etched by a same predetermined amount of etchant, some PCBs with relative small size may be over-etched, and some PCBs with relative large size may be under-etched. In such cases the electrical properties of the PCBs are affected.
What is needed, therefore, is an apparatus for wet processing a substrate which can overcome the above-described problem.